What is the formula for converting density units?

Every density unit can be converted through a common base unit, usually kilograms per cubic metre (kg/m3). Multiply your value by its conversion factor to kg/m3, then divide that result by the conversion factor of the unit you want. For example, to convert 1 g/cm3 to lb/ft3, first multiply by 1000 to get 1000 kg/m3, then divide by 16.01846 (the kg/m3 value of 1 lb/ft3) to get 62.4280 lb/ft3.

How do I convert g/cm3 to kg/m3?

Multiply the value in g/cm3 by 1000 to get kg/m3, because 1 gram per cubic centimetre equals 1000 kilograms per cubic metre. Water has a density of 1 g/cm3, which equals 1000 kg/m3. This is the most common density conversion used in engineering, chemistry, and materials science.

Why do g/cm3 and kg/L give the same number?

Because 1 cubic centimetre is exactly equal to 1 millilitre, and 1000 millilitres make up 1 litre. So a density expressed in grams per cubic centimetre is numerically identical to the same density expressed in kilograms per litre. Water at 1 g/cm3 is therefore also exactly 1 kg/L.

Density Conversion Calculator

This calculator converts a density figure between six units used across New Zealand engineering, chemistry and trade contexts: kilograms per cubic metre (kg/m³), grams per cubic centimetre (g/cm³), kilograms per litre (kg/L), pounds per cubic foot (lb/ft³), pounds per US gallon (lb/gal) and ounces per cubic inch (oz/in³). You enter your density value, choose the unit it is currently in, and pick a second unit you want it converted to and highlighted. The calculator instantly returns your original value, the converted value in your chosen unit, and the conversion factor you multiply by to get there. Below that sits a full table showing your value expressed in every one of the six units at once, plus the step by step working: the value you entered, its conversion to the common base unit of kg/m³, and the final conversion from that base into your target unit. A reference table of everyday material densities, such as fresh water, seawater, air, aluminium, steel and gold, gives you something to sanity check your result against. Use this tool whenever you need to move between metric and imperial density units, for example checking an imported material spec sheet quoted in lb/ft³ against a New Zealand supplier's kg/m³ figure. Reference densities shown are approximate values at around 20 degrees Celsius and atmospheric pressure, since real materials vary with temperature and composition.

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Reference values checked 2026 Standard SI and imperial density conversion factors.

1. Enter Your Value

Density value

Unit of your value

2. Unit To Highlight

Convert to (also shown in table of all units below)

Conversion Result

Your Value

1.0000

g/cm3

Converted Value
1,000.00
kg/m3

Conversion Factor

1,000.000000

Multiply your value by this

Your Value in All Common Density Units

Unit	Value	1 unit equals in kg/m³

Conversion Working

Step 1: value entered1.0000 g/cm3

Step 2: convert to base (kg/m³)1,000.0000 kg/m3 (×1000)

Step 3: convert base to target unit÷ 1 (kg/m3 factor)

Result1,000.00 kg/m3

Reference Densities (approx, 20°C)

Fresh water1.000 g/cm³ / 1000 kg/m³

Seawater1.025 g/cm³ / 1025 kg/m³

Air (sea level)0.00120 g/cm³ / 1.20 kg/m³

Aluminium2.70 g/cm³ / 2700 kg/m³

Steel7.85 g/cm³ / 7850 kg/m³

Gold19.30 g/cm³ / 19300 kg/m³

Summary: Enter a density value above.

How Density Unit Conversion Works

Density describes how much mass is packed into a given volume, and it can be expressed in many different units depending on the country, industry, or textbook you are using. New Zealand and most of the world use SI units such as kilograms per cubic metre (kg/m³) or grams per cubic centimetre (g/cm³), while some older engineering references and American sources still use pounds per cubic foot (lb/ft³) or pounds per US gallon (lb/gal). Because density is simply mass divided by volume, converting between units means adjusting for both the mass unit (grams, kilograms, pounds, ounces) and the volume unit (cubic centimetres, cubic metres, litres, cubic feet, US gallons, cubic inches) at the same time.

Conversion Factors to kg/m³

Unit	1 unit = kg/m³
1 g/cm³	1,000 kg/m³
1 kg/L	1,000 kg/m³
1 lb/ft³	16.01846 kg/m³
1 lb/gal (US)	119.8264 kg/m³
1 oz/in³	1,729.994 kg/m³

To convert any density value, first multiply it by the conversion factor of its starting unit to get the value in kg/m³ (the common base unit). Then divide that base value by the conversion factor of whichever unit you want to convert to. This two-step process (convert to base, then convert from base) works for any pair of units without needing a separate formula for every combination.

Worked Example

Convert 1 g/cm³ to kg/m³. Step 1: 1 g/cm³ is the value entered. Step 2: multiply by the g/cm³ factor of 1000 to get the base value of 1000 kg/m³. Step 3: since the target unit is also kg/m³, no further division is needed. Result: 1000 kg/m³. This matches the calculator's default result above, and is the standard reference density of water.

Common Density Conversions

From	To	Multiply by
g/cm³	kg/m³	1,000
kg/m³	g/cm³	0.001
g/cm³	lb/ft³	62.4280
lb/ft³	kg/m³	16.01846
kg/m³	lb/gal (US)	0.0083454
g/cm³	oz/in³	0.5780

Why This Matters

Density conversion is used constantly in engineering, chemistry, construction, and shipping. Engineers convert between kg/m³ and lb/ft³ when working from imperial reference tables or American-made equipment specifications. Chemists convert g/cm³ (or the equivalent g/mL) into kg/m³ when working with the ideal gas law or fluid mechanics equations that expect SI units. Tradespeople estimating the weight of a tank of liquid or a delivered load of aggregate use density conversions to move between the units their supplier quotes and the units their calculations need. Getting the conversion factor wrong by a factor of 1000 (for example, confusing g/cm³ with kg/m³) is a common and costly error, so this calculator shows the full working alongside the answer.

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Sources: NIST Guide for the Use of the International System of Units (SI), NIST Special Publication 811. Conversion factors for lb/ft³, lb/gal (US) and oz/in³ derived from standard imperial to SI definitions (1 lb = 0.45359237 kg, 1 ft = 0.3048 m, 1 US gal = 3.785411784 L, 1 in = 0.0254 m).

This calculator provides standard unit conversions only. Density values for real materials vary with temperature, pressure and composition, so reference densities listed here are approximate and given at typical conditions (around 20°C and atmospheric pressure) unless stated otherwise.